We have continued to improve our 3-D visualization software, IMOD. Our main emphasis recently has been on fixing bugs and on improving the model display portion of the software, to facilitate our analysis of very large models, such as those of the Golgi complex. For example, the ability to save a set of views of the model has been significantly enhanced by including the properties of the individual objects in the saved information. Relevant properties include color and lighting characteristics, the position of a clipping plane, and whether the object is on or off. A wide range of displays including different color or lighting schemes and different subsets of the objects can thus be saved as part of a single model file, obviating the need to save multiple copies of a large model and making it easy to switch between and edit these views. A minor version update (Imod 2.10) incorporating these recent changes was released on our web site in July. There continues to be strong interest in this software. An analysis of our web server records shows that from October 10, 1997 to August 24, 1998 (10.5 months), the software was downloaded to 98 distinct sites. Most sites obtained the version for SGI computers but 24 obtained a version that runs on Sun computers. We also provide source code to non-profit groups upon request (3 groups so far in 1998).